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International audience; This study aims at suggesting a new approach to peri-implant healing models, providing a set of taxis-diffusion-reaction equations under the combined influence of mechanical and biochemical factors. Early events of osseointegration were simulated for titanium screw implants inserted into a pre-drilled trabecular bone environment, up to twelve weeks of peri-implant bone healing. Simulations showed the ability of the model to reproduce biological events occurring at the implant interface through osteogenesis. Implants with shallow healing chamber showed higher proportions of lamellar bone, enhanced by the increase of mechanical stimulation. Osteoconduction was observed through the surface treatment model and similar bone healing patterns compared to in vivo studies.

Objective: The aim of this study was to assess, through biological analysis, the local effects and osseointegration of dental implants incorporating surface micro/nanofeatures compared to implants of identical design without surface treatment. Background: Known to impact bone cell behavior, surface chemical and topography modifications target improved osseointegration and long-term success of dental implants. Very few studies assess the performance of implants presenting both micro-and nanofeatures in vivo on the animal models used in preclinical studies for medical device certification. Methods: Implant surfaces were characterized in terms of topography and surface chemical composition. After 4 weeks and 13 weeks of implantation in sheep femoral condyles, forty implants were evaluated through micro-computed tomography, histopathologic, and histomorphometric analyses. Results: No local adverse effects were observed around implants. Histomorphometric analyses showed significantly higher bone-to-implant contact in the coronal region of the surface treated implant at week 4 and week 13, respectively 79.3$\pm$11.2% and 86.4$\pm$6.7%, compared to the untreated implant's 68.3$\pm$8.8% and 74.8$\pm$13%. Micro-computed tomography analyses revealed that healing patterns differed between coronal and apical regions, with higher coronal boneto-implant contact at week 13. Histopathologic results showed, at week 13, bone healing around the surface treated implant with undistinguishable defect margins while the untreated implant still presented bone condensation and traces of the initial drill defect. Conclusion: Our results suggest that the surface treated implant not only shows no deleterious effects on local tissues but also promotes faster bone healing around the implant. (word count: 241, Journal of Periodontal Research, Wiley, 2021

International audience; B-mode ultrasound (echography) has long been a first-line examination for the diagnosis of many diseases in children. The other modalities, such as X-ray or magnetic resonance imaging, are often associated with inconveniences of variable importance (cost, irradiation, sedation, accessibility) that are constraining for pediatric applications [1]. But B-mode ultrasound has difficulty penetrating bone and the locks associated with the in-vivo configuration are still numerous: image resolution and the contrast in the deep zone; accessibility of anatomical sites, or in between the two leg and arm bones. Ultrasonic Computed Tomography (USCT) is a relevant modality to bone tissues imaging [2], [3]. The acquisition geometry of the signals is no longer linear nor sectoral, as in B-mode ultrasound, but circular in the orthogonal plane, and based on a multiplexed dual-frequency 2D-ring antenna allowing electronical and mechanical scanning. The antenna supports 8 fixed transducers distributed over 360�. The Mistras-Eurosonic? multiplexer is equipped with an 8-by-8 parallel-channel acquisition system. The 8 transducers are Imasonic? piezo-composite transducers with a center frequency of 1MHz and 2.25MHz. Each transducer is 60 mm high and 56 mm in diameter. These transducers have cylindrical focusing with a focal length of 150 mm, a lateral aperture size of 40 mm and an axial aperture size of 30 mm. The slice thickness is 3 mm. Results obtained on rectified non-circular cylindrical tubes, on paired bones (Sawbones�) are presented. References [1] P. Petit et al., ?Am. J. Roentgenol., vol. 176, no. 4, pp. 987?990, Apr. 2001. [2] P. Lasaygues et al., Proceedings of the Int. Workshop on MUST, Speyer, Germany, 2017. [3] S. Bernard, et al., Phys. Med. Biol., vol. 62, no. 17, pp. 7011?7035, Aug. 2017. Acknowledgements This research was supported by the Provence-Alpes-Côte d'Azur ? PACA Regional Council, under Grant No.2016₀2696.

International audience; The knowledge of local stress distribution in hand joints is crucial to understand injuries and osteoarthritis occurrence. However, determining cartilage contact stresses remains a challenge, requiring numerical models including both accurate anatomical components and realistic tendon force actuation. Contact forces in finger joints have frequently been calculated but little data is available on joint contact pressures. This study aimed to develop and assess a hybrid biomechanical model of the index finger to estimate in-vivo joint contact pressure during a static maximal strength pinch grip task. A finite element model including bones, cartilage, tendons, and ligaments was developed, with tendon force transmission based on a tendon-pulley system. This model was driven by realistic tendon forces estimated from a musculoskeletal model and motion capture data for six subjects. The hybrid model outputs agreed well with the experimental measurement of fingertip forces and literature data on the physiological distribution of tendon forces through the index finger. Mean contact pressures were 6.9 ± 2.7MPa, 6.2 ± 1.0 MPa and 7.2 ± 1.3MPa for distal, proximal interphalangeal and metacarpophalangeal joints, respectively. Two subjects had higher mean contact pressure in the distal joint than in the other two joints, suggesting a mechanical cause for the prevalence of osteoarthritis in the index distal joint. The inter-subject variability in joint contact pressure could be explained by different neuromuscular strategies employed for the task. This first application of an effective hybrid model to the index finger is promising for estimating hand joint stresses under daily grip tasks and simulating surgical procedures.

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International audience; Introduction This work compares the biomechanical resistance of five modes of fixation coracoid bone-block fixation during Latarjet open-air or arthroscopic procedures. The hypothesis is that these systems are equivalent. Material and Methods Latarjet procedures were performed on cadavers, then the samples were subjected to an increasing tension until the fixation failed. Five systems were tested: 2 malleolar screws, 1 screw with washer, 2 3.5mm self-compressive screws, 1 4mm self-compressive screw associated with 1 3mm self-compressive screw, and endobutton. The main judgement criterion was the strength necessary for the failure of the fixation. The secondary criterion was the stiffness of the assembly. Results The single malleolar screw fixing has a lower breaking thresehold than other fixings. There is no difference in strength concerning the other systems. The average strength is greater than the stresses of a shoulder during daily life activities. There is no difference regarding the secondary criterion. Conclusion The use of a single screw is insufficient, but the other systems seems reliable. The use of small diameter self-compressive cannulated screws can provide a better result. This biomechanical work must be validated in clinical studies.

International audience; Purpose Patient-specific cutting guides (PSCGs) have been advocated to improve the accuracy of deformity correction in opening-wedge high-tibial osteotomies (HTO). It was hypothesized that PSCGs for HTO would have a short learning curve. Therefore, the goals of this study were to determine the surgeons learning curve for PSCGs used for openingwedge HTO assessing: the operating time, surgeons comfort levels, number of fluoroscopic images, accuracy of postoperative limb alignment and functional outcomes. Methods This prospective cohort study included 71 consecutive opening-wedge HTO with PSCGs performed by three different surgeons with different experiences. The operating time, the surgeon's anxiety levels evaluated using the Spielberger State-Trait Anxiety Inventory (STAI), the number of fluoroscopic images was systematically and prospectively collected. The accuracy of the postoperative alignment was defined by the difference between the preoperative targeted correction and the final post-operative correction both measured on standardized CT-scans using the same protocol (ΔHKA, ΔMPTA, ΔPPTA). Functional outcomes were evaluated at 1 year using the different subscores of the KOOS. Cumulative summation (CUSUM) analyses were used to assess learning curves. Results The use of PSCGs in HTO surgery was associated with a learning curve of 10 cases to optimize operative time (mean operative time 26.3 min ± 8.8), 8 cases to lessen surgeon anxiety levels, and 9 cases to decrease the number of fluoroscopic images to an average of 4.3 ± 1.2. Cumulative PSCGs experience did not affect accuracy of post-operative limb alignment with a mean: ΔHKA = 1.0° ± 1.0°, ΔMPTA = 0.5° ± 0.6° and ΔPPTA = 0.4° ± 0.8°. No significant difference was observed between the three surgeons for these three parameters. There was no statistical correlation between the number of procedures performed and the patient's functional outcomes. Conclusion The use of PSCGs requires a short learning curve to optimize operating time, reduce the use of fluoroscopy and lessen surgeon's anxiety levels. Additionally, this learning phase does not affect the accuracy of the postoperative correction and the functional results at 1 year. Level of evidence II: prospective observational study.

Introduction Isolated lateral compartment osteoarthritis of the knee (LCOA) is 10 times less frequent than medial compartment involvement. Long-term assessments of unicompartmental knee arthroplasty (UKA) in this indication are rare, with small series. Hypothesis Survival and functional outcome of lateral UKA in a large series are quite acceptable; the strategy is suited for isolated LCOA. Material and method A multicenter retrospective study in 6 French health establishments included all lateral UKAs performed between January 1988 and September 2014. Clinical data (range of motion, International Knee Society (IKS) knee and function scores, satisfaction), paraclinical data (radiologic angles) and complications were prospectively entered in medical files during follow-up and analyzed retrospectively at end of follow-up. Results During the study period, 311 lateral UKAs were performed in 295 patients, using 5 fixed-bearing implant models. Twenty-eight patients died within 5 years, and 15 (4.8%) were lost to follow-up. The series thus comprised 268 lateral UKAs in 63 male and 205 female patients, with a mean age of 68.8 ± 10.5 years, including 7 cases of post-traumatic osteoarthritis and 4 of aseptic osteonecrosis. Mean follow-up was 9.1 years (range, 5-23 years), implant survivorship with failure defined as all-cause revision surgery was 85.4% at 10 years and 79.4% at 20 years. At last follow-up, IKS knee score was 87.0 and IKS function score 80.2. Maximal flexion was 125°. 94.3% of patients were satisfied or very satisfied. The main cause of revision surgery was osteoarthritis in another knee compartment (66,7%, n = 26). Conclusion Lateral UKA showed good survivorship, comparable to medial UKA, with good functional results and excellent long-term satisfaction. Level of evidence IV, retrospective cohort study.

International audience; Background: During medial unicompartmental knee arthroplasty (UKA), tibial tray implantation requires compromise between bone coverage and rotational position. It was hypothesized that morphometric tibial tray (MTT) would improve implant positioning and subsequently clinical outcomes as compared to symmetric tibial tray (STT). Methods: A total of 106 patients who underwent medial UKA in our department between January 2017 and March 2018 were included matched on gender and age (53 in each group). Inclusion criteria were symptomatic medial femorotibial osteoarthritis, functional anterior cruciate ligament, primary arthritis, or osteonecrosis. Rotation of the tibial implant, tibial bone coverage, medial and posterior overhang were assessed with a postoperative computed tomography scan. The Knee Society Score (KSS), the Knee injury and Osteoarthritis Outcome Score Short Form (KOOS SF), and the quality of life score EuroQoL 5-Dimensions 3-Levels (EQ5D3L) were assessed at a minimum of 1-year follow-up. Results: Implants of the STT group exhibited more external rotation (6.3 ± 4.02 vs 4.6 ± 3.59 ; P ¼ .04), and medial and posterior overhang >3 mm (35% vs 0% and 22% vs 0%; P < .0001) but no difference for tibial bone coverage (97.3% ± 11.35% vs 94.7% ± 10.89%; P ¼ .23). Global KSS (188.6 ± 6.6 vs 175.2 ± 31.7; P < .01), KOOS SF (16.9 ± 6.1 vs 22.5 ± 11.8; P < .003), and EQ5D3L (1 ± 0.1 vs 0.9 ± 0.2; P < .001) were higher in MTT group. According to the multivariate analysis, MTT had a positive independent effect on the KSS, KOOS SF, and EQ5D3L. Conclusion: The use of an MTT in medial UKA allowed better implant positioning when decreasing the rate of overhang; superior short-term clinical outcomes were found as compared to STT.

Background Although the utility of robotic surgery has already been proven in cadaveric studies, it is our hypothesis that this newly designed robotically assisted system will achieve a high level of accuracy for bone resection. Therefore, we aimed to analyze in a cadaveric study the accuracy to achieve targeted angles and resection thickness. Methods For this study, 15 frozen cadaveric specimens (30 knees) were used. In this study, Zimmer Biomet (Warsaw, IN) knees, navigation system, and robot (ROSA Knee System; Zimmer Biomet) were used. Eight trained, board-certified orthopedic surgeons performed robotically assisted total knee arthroplasty implantation using the same robotic protocol with 3 different implant designs. The target angles obtained from the intraoperative planning were then compared to the angles of the bone cuts performed using the robotic system and measured with the computer-assisted system considered to be the gold standard. For each bone cut the resection thickness was measured 3 times by 2 different observers and compared to the values for the planned resections. Results All angle mean differences were below 1° and standard deviations below 1°. For all 6 angles, the mean differences between the target angle and the measured values were not significantly different from 0 except for the femoral flexion angle which had a mean difference of 0.95°. The mean hip-knee-ankle axis difference was −0.03° ± 0.87°. All resection mean differences were below 0.7 mm and standard deviations below 1.1mm. Conclusion Despite the fact that this study was funded by Zimmer Biomet and only used Zimmer Biomet implants, robot, and navigation tools, the results of our in vitro study demonstrated that surgeons using this new surgical robot in total knee arthroplasty can perform highly accurate bone cuts to achieve the planned angles and resection thickness as measured using conventional navigation.

Background Accelerometer-based navigation is a handheld navigation tool that was introduced to offer a simpler technique compared with more-cumbersome computer-assisted surgery (CAS). Considering the increasing number of adopters, it seems important to evaluate the potential clinical benefits of this technology compared with conventional TKA. Questions/purposes In this systematic review, we asked: (1) Is accelerometer-based navigation more accurate than conventional TKA? (2) Does accelerometer-based navigation provide better functional outcome than conventional TKA? (3) Does accelerometer-based navigation increase surgical time or decrease the risk of complications or reoperations compared with conventional TKA? Methods This systematic review included all comparative prospective and retrospective studies published in the MEDLINE/PubMed and Cochrane libraries over the last 10 years. Inclusion criteria were all studies in English that compared accelerometer-based navigation with conventional TKA. Eleven studies met these criteria with 621 knees in accelerometer-based navigation group and 677 knees in conventional TKA group. Results related to alignment, objective and subjective functional scores, duration of surgery, complications and reoperations were extracted and compared between accelerometer-based-navigation and conventional TKA. Methodological quality was assessed using Methodological Index for Non-Randomized Studies (MINORS) tool (for nonrandomized control trials) and Cochrane Risk of Bias (for randomized control trials (RCTs). All studies with fair or better quality were included. Four RCTs and six nonrandomized studies comparing accelerometer-based navigation to conventional TKA were found. Results Inconsistent evidence on mechanical axis alignment was found, with five of nine studies slightly favoring the accelerometer-based navigation group, and the other four showing no differences between the groups. Only two of eight studies favored accelerometer-based navigation in terms of tibial component alignment in the coronal plane; the other six found no between-group differences. Similarly, mixed results were found regarding other metrics related to component alignment; a minority of studies favored accelerometer-based navigation by a small margin, and most studies found no between-group differences. Only three studies evaluated functional outcome and none of them showed a difference in range of motion or patient-reported outcomes. Most studies, six of seven, found no between-group differences concerning surgical time; one study demonstrated a slight increase in time with accelerometer-based navigation. There were no between-group differences in terms of the risk of complications, which generally were uncommon in both groups, and no reoperations or revisions were reported in either group. Conclusions We found conflicting evidence about whether accelerometer-based navigation reduces the number of coronal-plane outliers or improves alignment to a clinically important degree, and we found no evidence that it improves patient-reported outcomes or reduces the risk of complications or reoperations. Accelerometer-based navigation may increase surgical time. The overall quality of the evidence was low, which suggested that any observed benefits were overestimated. Given the absence of higher-quality evidence demonstrating compelling benefits of this accelerometer-based navigation technology, it should not be widely adopted. Level of evidence Level III, therapeutic study.

Place: Germany; PURPOSE: The distal femoral varization osteotomy (DFVO) by a lateral opening wedge osteotomy is an established intervention for patients suffering from lateral femoro-tibial osteoarthritis on a genu valgum deformity. In order to improve the accuracy of this correction, the use of a customized cutting guide (PSI) has been proposed as an alternative to conventional technique. The objective of our study was to compare the accuracy of post-operative alignment following DFVO in the coronal and sagittal plane using either a conventional abacus technique or PSI guide. METHOD: Twenty-one patients that underwent lateral opening wedge osteotomy from a technique using PSI based on 3D CT-scans were matched 1:1 to 21 patients operated on using a conventional technique (pre-operative planning performed on standard radiographs). The accuracy of the correction was analyzed, comparing coronal and sagittal mechanical post-operative angles with pre-operative planning. RESULTS: With regard to alignment in the coronal plane (HKA correction), our study demonstrated a significant improvement in the accuracy of the correction obtained in the PSI group compared to the conventional group (0.43 ± 0.50 vs 3.95 ± 1.64 p \textless 0.001). In the sagittal plane (PDFA correction), we also found a significant improvement in correction accuracy in the PSI group (0.52 ± 0.60 vs 3.10 ± 1.83 p \textless 0.001). There was a significant decrease in operating time (delta 7.7 ± 3.07 (1.5-13.9) (p = 0.0.161) and fluoroscopic images taken (6.9 ± 0.54 (5.8-8) p \textless 0.001). CONCLUSION: Our results suggest that the use of PSI in DFVO improves the accuracy of correction in both the coronal and sagittal planes compared to conventional techniques.

Background:Three main meniscal preservation methods have been used over the past decade: cryopreservation, freezing, and freezing with gamma irradiation.Hypothesis:All 3 preservation methods will result in similar biomechanical properties as defined by tensile and compression testing.Study Design:Controlled laboratory study.Methods:A total of 24 human lateral menisci were collected from patients who underwent total knee arthroplasty. Inclusion criteria were patients younger than 70 years with primary unilateral (medial) femorotibial knee osteoarthritis. Each meniscus was divided into 2 specimens cross-sectionally. One specimen was systematically cryopreserved and constituted the control (Cy; –140°C), and the other specimen was used for either the simple frozen group (Fr; –80°C) or the frozen+irradiated group (FrI; –80°C + 25-kGy irradiation). Compression and tensile tests were performed to analyze the elasticity modulus (Young modulus) in compression, the elasticity modulus in tension, the tensile force at failure, and the rupture profile of the tensile stress-strain curve.Results:A significant difference in the mean compression elasticity modulus was observed between the Cy and Fr groups (28.86 ± 0.77 vs 37.26 ± 1.08 MPa, respectively; P < .001) and between the Cy and FrI groups (28.86 ± 0.77 vs 45.92 ± 1.09 MPa, respectively; P < .001). A significant difference in the mean tensile elasticity modulus was also observed between the Cy and Fr groups (11.66 ± 0.97 vs 19.97 ± 1.37 MPa, respectively; P = .008) and between the Cy and FrI groups (11.66 ± 0.97 vs 45.25 ± 1.39 MPa, respectively; P < .001). There were no significant differences between the control and study groups in tensile force at failure. The analysis of the stress-strain curve revealed a slow-slope curve with a nonabrupt rupture (ductile material) for the Cy samples versus a clear rupture of the curve for the Fr and FrI samples (more fragile material).Conclusion:Cryopreservation allows for more elastic and less fragile tissue compared with simple freezing or freezing plus irradiation.Clinical Relevance:The study results exhibit the detrimental effect of simple freezing and freezing plus irradiation on human meniscal mechanical properties. If these effects occur in menisci prepared for allograft procedures, important differences could appear in the graft’s mechanical behavior and thus patient outcomes.

The gold standard for treating chronic periprosthetic joint infection is still considered to be double-stage exchange revision. The purpose of this review is to analyse the difference in terms of eradication rates and functional outcome after single- and double-stage prosthetic exchange for chronic periprosthetic joint infection around the knee. We reviewed full text articles written in English from 1992 to 2018 reporting the success rates and functional outcomes of either single-stage exchange or double-stage exchange for knee arthroplasty revision performed for chronic infection. In the case of double-stage exchange, particular attention was paid to the type of spacer: articulating or static. In all, 32 articles were analysed: 14 articles for single-stage including 687 patients and 18 articles for double-stage including 1086 patients. The average eradication rate was 87.1% for the one-stage procedure and 84.8% for the two-stage procedure. The functional outcomes were similar in both groups: the average Knee Society Knee Score was 80.0 in the single-stage exchange group and 77.8 in the double-stage exchange. The average range of motion was 91.4° in the single-stage exchange group and 97.8° in the double-stage exchange group. Single-stage exchange appears to be a viable alternative to two -stage exchange in cases of chronic periprosthetic joint infection around the knee, provided there are no contra-indications, producing similar results in terms of eradication rates and functional outcomes, and offering the advantage of a unique surgical procedure, lower morbidity and reduced costs. Cite this article: EFORT Open Rev 2019;4:495-502. DOI: 10.1302/2058-5241.4.190003

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International audience; Revisions TKAs are being completed with uncemented constructs more frequently. We hypothesized that tantalum cones could be an efficient carrier of antibiotics in uncemented procedures. We aimed to compare the release of vancomycin between (i) tantalum and smooth stainless cylinders; (ii) different concentrations of vancomycin; and (iii) different durations of bathing. Specifically designed tantalum cylinders were bathed in a vancomycin solution with various durations of baths. We investigated rinses between each interval as well as the dose of vancomycin. Vancomycin concentrations were determined in each group by fluorescence polarization immunoassay at different intervals (1 h, days 1, 2, 3, 5). At 1 h, the mean vancomycin concentration for the 1‐hour soaking group was 3,172 μg/ml, whereas mean concentration for the smooth stainless steel group was 39.37 μg/ml (p

Place: France; INTRODUCTION: Arthroscopy has enabled minimally invasive procedures to be developed to treat tibial plateau fracture. The aim of the present study was to assess and compare clinical and radiological results between arthroscopically assisted reduction and internal fixation (ARIF) and open reduction and internal fixation (ORIF) procedures. The study hypothesis was that, in selected tibial plateau fractures, ARIF provides (1) clinical results comparable to those of ORIF, and (2) satisfactory reduction and stable fixation. MATERIAL AND METHOD: A retrospective multicenter study included adult patients with tibial plateau fracture (Schatzker I to III), over the period January 2010 to December 2014, enabling a minimum 2 years' follow-up. Clinical and radiological data (RoM, IKDC, HSS, Lysholm) were collected at 3, 6 and 12 months and at last follow-up. A total of 317 patients (317 fractures), aged 48±14 years (range, 18-82 years) were followed up for 38±23 months (range, 24-90 months), with 77 fractures (24%) in the ARIF group and 240 (76%) in the ORIF group. RESULTS: Clinically, there were no significant inter-group differences for active flexion, passive or active extension or Lysholm and IKDC scores, with significant differences for HSS (ARIF: 74±29; ORIF: 70±31; p\textless0.01) and passive flexion (ARIF: 130±19° (range, 80-160°); ORIF: 130±15.965° (range, 60-140°); p\textless0.05). Radiologically, there were no significant inter-group differences for reduction quality, lower-limb mechanical axis or signs of osteoarthritis. There were no secondary displacements. There were 7 complications (7/77, 9%) in the ARIF group and 18 (18/240, 8%) in the ORIF group, and 6 surgical revisions for early infection (2 ARIF, 4 ORIF), with no significant inter-group differences. DISCUSSION: The study hypothesis was confirmed: in Schatzker I-III fractures, ARIF provided clinical results comparable to those of ORIF, with satisfactory reduction and stable fixation. ARIF has its place in the treatment of tibial plateau subsidence and/or separation fracture. LEVEL OF EVIDENCE: III, retrospective comparative study.

Place: United States

Place: France; BACKGROUND: Non-operative treatment for impacted femoral neck fractures is a now rarely used strategy whose indications are controversial. No outcome predictors have been convincingly identified, in part due to the small sizes of available studies. We conducted a large retrospective study with the following objectives: (1) to evaluate the percentage of patients older than 65 years of age with non-operatively treated Garden I femoral neck fractures who experience secondary displacement, (2) to identify predictors of secondary displacement, and (3) to determine the frequency of non-operative treatment failure due to any cause and requiring joint replacement surgery. HYPOTHESIS: Non-operative treatment is reliable in patients older than 65 years of age with Garden I femoral neck fractures. MATERIAL AND METHODS: Approval was obtained from the French data protection authority to conduct a retrospective observational study of information in the Marseille university hospitals database. Consecutive patients who were older than 65 years of age at traumatology department admission for Garden I femoral neck fractures managed non-operatively between January 2007 and December 2017 were included. Non-operative treatment consisted in a walking test on day 1 followed by radiographs on days 2, 7, 14, 21, and 45 and after 3 and 12 months. Patients with secondary displacement underwent hip arthroplasty. Demographic data, cognitive performance, and radiological parameters were collected for each patient. We evaluated the rates of secondary displacement avascular necrosis, and non-union. RESULTS: We included 298 patients with a mean age of 82 years (range, 65-101). Mean follow-up was 5±3 years. Secondary displacement occurred in 91 (30%) patients, at a mean of 16 days (range 2-45 days) after the fracture. Avascular necrosis of the femoral head developed in 13 (4.3%) patients and non-union in 11 (3.7%) patients. Secondary displacement was significantly associated with hypnotic treatment (OR, 4.1; 95%CI, 2.2-7.5; p=0.039), institutionalisation (OR, 6.7; 95%CI, 3.1-14.8; p=0.028), a history of repeated falls (OR, 13.5; 95%CI, 6.3-8.4; p\textless0.0001), having three or more comorbidities (OR, 3.2; 95%CI, 1.7-5.8; p=0.046), and having dementia (OR, 3.5; 95%CI, 1.7-6.9; p=0.0003). Secondary displacement occurred in 18 (12%) of the 151 community-dwelling patients with normal cognition and no history of repeated falls compared to 37 (75%) of the 50 institutionalised patients with dementia. DISCUSSION: Non-operative treatment was effective in 196 (66%) of 298 patients with Garden I femoral neck fractures. Significant risk factors for secondary displacement were dementia, institutionalisation, hypnotic treatment, multiple comorbidities, and a history of repeated falls. Of 151 community-dwelling patients with normal cognition and no repeated falls, 133 (88%) achieved a full recovery with non-operative treatment alone. LEVEL OF EVIDENCE: IV, retrospective cohort study.

Background Current trends in patient management include decreasing hospital stay lengths and reductions in available material and human resources. A shortening of hospital stays in university hospitals has been documented over the last decade. However, to our knowledge, no study has assessed possible relationships linking shorter stays to staffing levels or complication rates. The objectives of this study were: 1) to assess changes in case volume in a university orthopaedics and trauma surgery department between 2006 and 2016, 2) and to look for correlations linking these changes to staffing levels and the rates of significant complications, including the number of hip dislocations after total hip arthroplasty (THA) and the number of infections and complications resulting in malpractice litigation after hip, knee, or shoulder arthroplasty. Hypothesis The case volume increased during the study period, whereas resources remained unchanged or decreased. Material and methods A retrospective study was performed using the electronic database of an orthopaedics and trauma surgery department. Data collected between 2006 and 2016 were analysed. Mean hospital stay length, patient age, and surgical volume were recorded, and changes over time in case volume for trauma surgery and scheduled arthroplasties were evaluated. Changes in staffing levels and rates of complications (dislocation after THA and infections and complications resulting in malpractice litigation) between 2006 and 2016 were assessed. Only arthroplasty procedures performed in the department were considered for the study of complications and litigation. Results Between 2006 and 2016, mean hospital stay decreased from 8.7 ± 10.8 days (range, 0–141 days) in to 7.0 ± 9.4 days (range, 0–150 days). Mean patient age increased from 54.4 ± 21.2 years (range, 11.7–100.9 years) in 2006 to 59.3 ± 20.9 years (range, 13.2–103.1 years) in 2016. The total number of procedures rose from 2158 in 2006 to 3100 in 2016 (+43.6%). The number of THAs increased by 16.2% and the number of total knee arthroplasties by 96.7%. The number of operations for trauma increased from 725 in 2006 to 1135 in 2016 (+56.0%). During the study period, the number of hospital beds declined from 70 to 55. No increase was seen in the frequencies of dislocation after THA (3/284 [1.4%] in 2006 and 4/330 [1.2%] in 2016) or prosthetic joint infection (5/439 [1.1%] in 2006 and 6/657 [0.9%] in 2016). In contrast, malpractice suits filed by patients after arthroplasty increased from 1/439 (0.2%) in 2006 to 8/657 (1.2%) in 2016. Conclusion Over the last decade, trauma and arthroplasty surgical volumes increased substantially, whereas staffing levels remained unchanged and number of beds diminished. The frequency of significant complications such as dislocation after THA did not increase. In contrast, a marked rise was seen in malpractice litigation. However, the increased volume with unchanged resources found in this study should be interpreted in the light of the marked increase in patient dependency and of our role as a referral centre managing patients with complications after surgery performed at other institutions. Level of evidence IV, retrospective observational study.

International audience; Introduction: Injectable cements have been developed to improve fixation's stability and thus obtain early return to adequate joint function. We aimed to compare post-operative radiographic and clinical outcomes of patients suffering from a complex tibial plateau fracture (TPF) fixed with calcium-phosphate bone substitutes (CPBS) augmentation to a matched group of patients with identical fracture pattern, treated with the same fixation's type, but augmented with bone grafting. Methods: After local ethic committee approval, we retrospectively identified in a prospectively collected database, patients with complex comminuted metaphyseal and epiphysial bicondylar TPF (Schatzker type VI) admitted in our emergency department between January 2011 and December 2013. From those, 23 patients (14 males, 9 females) were treated with CPBS (Quickset-CP (R), Graftys, Aix-en-Provence, France) fixation augmentation. Patients' mean age were 44.4years. We then created a control group using a 1:1 matching process on gender, age, fracture pattern, and method of fixation. Patients were evaluated prospectively at 3, 6, and then every sixmonths using radiographic (AP/ML views) and clinical criteria (knee osteoarthritis outcomes score (KOOS) and EuroQOL-5D). Results: Articular step-off and variation of articular step-off were significantly lower in the CPBS groups (mean step-off 1.41.9 (0.5-6.5 mm) and mean step-off Delta=0.3 +/- 0.4 (0.5-2.2 mm)) than in the control group (mean step-off 3.6 +/- 2.1 (1- 7.5 mm) and mean step-off Delta=2.2 +/- 2 (0.5-7 mm) p2mm and step-off Delta > 2 mm (respectively, 56 and 35%) than patients of the CPBS group (26 and 9%). Odd ratio of, respectively, 3.6 (95% CI (1.08-12.7) and p = 0.03) and 5.6 (95% CI (1.04-30.1) and p = 0.03).At mean follow-up of 29 months, KOOS pain subscore was significantly better in patients of the CPBS group (85.3 +/- 12.1) than in control patients (74.2 +/- 10.4 and p = 0.03). Conclusion: The present study demonstrates that calcium-phosphate bone substitute used as synthesis augmentation improves mid-term radiological outcomes of patients suffering from complex tibial plateau fracture. Series reporting outcomes from a larger number of patients and longer follow-up must confirm clinical benefits and safety of this method.

Aim:The purpose of this study is to report the 20-year follow-up of a continuous series of 232 total hip arthroplasties (THAs) performed in patients aged less than 50 at the index surgery.Patients and methods:This is a retrospective monocentric study which reports the clinical, radiographical and survival results of 232 THAs performed with a custom cementless femoral stem in 212 patients evaluated at follow-up ranging from 14 to 27 years.Results:At the time of follow-up, the mean Harris Hip Score was 94.1 (range 48–100). The Hip disability and Osteoarthritis Outcome Score was >80 points in all 5 categories for 146 patients (68.9%). 18 hips (8.5%) showed radiographical femoral abnormalities. 23 hips (10.8%) underwent revision of the implants. 13 were isolated cup revisions. 3 more hips had bipolar revisions for aseptic loosening at 15, 20 and 21 years. Taking stem revision for aseptic loosening as an endpoint, survivorship was 96.8% at 20 years (95% confidence interval, 95.1–98.5; patients at risk 76) and 94.5% at 25 years (91.7–97.3; patients at risk 12).Conclusions:The results of this study confirm that THA using this custom-designed stem can provide excellent clinical and radiographical outcomes at a mean follow-up of 20 years in patients younger than 50. The individual 3D femoral stem and prosthetic neck has been able to restore extra- and intramedullary functional anatomy in this young and active cohort of patients.

Background: Three main meniscus preservation methods have been advocated: freezing (–80°C), freezing with gamma irradiation (–80°C + 25 kGy), and cryopreservation (–140°C). Hypothesis: All preservation methods will result in structural and architectural properties similar to those of fresh meniscus, defined as the gold standard. Study Design: Controlled laboratory study. Methods: Five human intact menisci were collected from 5 patients undergoing total knee arthroplasty. The inclusion criteria were patients 3) were cut inside of the white, or avascular, area of each specimen’s middle horn and divided into 4 groups: “fresh” control, frozen (–80°C), cryopreserved (–140°C), and frozen + irradiated (–80°C + 25 kGy). Specimens of the control group were evaluated at day 1, and specimens from the frozen, cryopreserved, and frozen + irradiated groups were evaluated after 1 month of storage. Evaluation was performed with electron microscopy according a validated protocol to analyze (1) mean diameters of the collagen fibers in longitudinal and transverse sections in 5 points per section and (2) validated architectural scores. Results: No significant difference was found between the control and cryopreserved groups regarding mean transverse and longitudinal diameters (transverse: 95.39 ± 15.87 nm vs 99.62 ± 19.23 nm, P = .1; longitudinal: 96.31 ± 13.96 nm vs 94.57 ± 16.42 nm, P = .1). Significant differences were found between the control and frozen groups (transverse: 95.39 ± 15.87 nm vs 70.20 ± 13.94 nm, P < .001; longitudinal: 96.31 ± 13.96 nm vs 71.28 ± 10.64 nm, P < .001) and the control and frozen + irradiated groups (transverse: 95.39 ± 15.87 nm vs 63.1 ± 15.57 nm, P < .001; longitudinal: 96.31 ± 13.96 nm vs 60.9 ± 14.8 nm, P < .001). Regarding architectural score calculation, there were significant differences between the control and frozen groups (4.5 ± 1.3 vs 2.3 ± 1.4, P = .02) and the control and frozen + irradiated groups (4.5 ± 1.3 vs 1.4 ± 0.9, P = .02). Conclusion: Cryopreservation is the only method that preserves fresh meniscus architectural specificities. Freezing and freezing + irradiation methods modify histologic properties of meniscal allograft. Irradiation deeply alters diameters and the organization of collagen fibers, and this method should be used with caution to preserve and sterilize meniscus tissue. Clinical Relevance: The results of our study exhibited detrimental effects of simple freezing and freezing + irradiation on the collagen network of sample meniscus. If those effects occur in menisci prepared for allograft procedures, important differences could appear on the basis of the preservation procedure in terms of the graft’s mechanical properties and, thus, the patient’s outcomes.

International audience; Introduction: The incidence of periprosthetic femoral fracture is constantly increasing, with high associated morbidity and mortality. Surgical treatment is guided by the Vancouver classification, but the influence of type of treatment on morbidity and mortality has been little analyzed. The theoretical advantage of implant revision over internal fixation is that it should allow earlier weight-bearing, although the impact of this on morbidity and mortality and autonomy has not been demonstrated. We conducted a case-control study, to assess the influence of type of treatment (implant revision or internal fixation) (1) on mobility and autonomy and (2) on morbidity and mortality. Hypothesis: The study hypothesis was that clinical results and morbidity and mortality do not differ between these two types of treatment. Methods: A retrospective study included 70 patients with a total of 71 femoral periprosthetic fractures treated between 2007 and 2014. Two treatment groups, comparable for mean age, gender and ASA and Parker scores, were studied. Mean age was 78 +/- 13.5 years (range, 23-95 years). Thirty-six fractures (50.7%) were treated by implant revision via a posterolateral approach, using a revision stem with (n=11) or without cement (n=25) (REVISION group); immediate postoperative weight-bearing was authorized. Thirty-five fractures (49.3%) were treated by open reduction and internal fixation, using a locking plate (ORIF group); weight-bearing was authorized only in the third month. Mean follow-up was 43 +/- 27 months (range, 0.75-107 months). Results: Autonomy on Parker score was reduced by 2 points at 1 year's follow-up. Mean preoperative scores were 7.32 +/- 1.79 (range, 3-9) and 7.43 +/- 1.79 (range, 4-9) in the REVISION and ORIF group, respectively, (p = 0.8), falling to 5.06 +/- 2.6 (range, 0-9) and 4.5 +/- 2.01 (range, 0-9) respectively at follow-up (p = 0.349). Sixteen patients in the REVISION group versus 13 in the ORIF group had made adaptations in their home or changed place of residence (p = 0.2). At last follow-up, 18 patients (28.6%) had died: 12 (37.5%) in the ORIF and 6 (19.3%) in the REVISION group (p < 0.05). Survival with death as endpoint at a mean 3.5 years was 88 +/- 11% in the REVISION group versus 51 +/- 11% in the ORIF group (p = 0.02). Three implant replacements were performed in each group (p = 0.83). Twelve medical or surgical complications occurred in the ORIF group (37.5%) and 11 in the REVISION group (34%) (p = 0.9). Conclusion: Implant revision for periprosthetic femoral fracture showed significantly lower overall mortality than internal fixation, without difference in terms of treatment failure or complications requiring revision surgery. (C) 2018 Published by Elsevier Masson SAS.

International audience; Introduction: Recent reports described possible mechanical factors in the development and aggravation of osteonecrosis of the femoral head (OFH), but these have yet to be confirmed on dedicated mechanical study. We therefore developed a 3D finite element model based on in-vivo data from patients with incipient OFH, with a view to determining whether the necrosis area was superimposed on the maximal stress area on the femoral head. Hypothesis: The location of the necrosis area is determined by stress on the femoral head. Material and method: All patients from the rheumatology department with early stage OFH in our center were investigated. Analysis of CT scans showed stress distribution on the head by 3D finite elements models, enabling determination of necrosis volume within the maximal stress area and of the percentage intersection of necrosis within the stress area (%I n/s: necrosis volume in stress area divided by total stress area volume and multiplied by 100) and of stress within the necrosis area (%I s/n: stress volume in necrosis area divided by total necrosis area volume and multiplied by 100). Results: Nineteen of the 161 patients assessed retrospectively for the period between 2006 and 2015 had incipient unilateral OFH, 10 of whom (4 right, 6 left) had CT scans of sufficient quality for inclusion. Mean age was 52 years (range, 37-81 years). Mean maximal stress was 1.63 MPa, mean maximal exported stress volume was 2,236.9 mm(3) and mean necrosis volume 6,291.1 mm(3). Mean %I n/s was 83% and mean %I s/n 35%, with no significant differences according to gender, age, side or stress volume. There was a strong inverse correlation between necrosis volume and %I s/n (R-2 = -0.92) and a strong direct correlation between exported stress volume and %I s/n (R-2 = 0.55). %I s/n was greater in small necrosis (< 7,000 mm(3)). Conclusion: OFH seems to develop within the maximal stress area on the femoral head. The present results need confirmation by larger-scale studies. We consider it essential to take account of these mechanical parameters to reduce failure rates in conservative treatment of OFH. (C) 2018 Elsevier Masson SAS. All rights reserved.

International audience; During the 1980s, fixed-bearing total knee arthroplasty (TKA) became a reliable, reproducible procedure with about 95% implant survival after 10 years. However, implant loosening and polyethylene wear became recognized as long-term causes of late failure. If loosening is related to abnormal strains at the bone-implant interface, polyethylene wear is mainly caused by the lack of congruency during implant motion, and thus surgeons tried to improve TKA's kinematics by introducing a second degree of freedom in their implants. Mobile-bearing knee replacements are based on a mobile polyethylene insert that articulates with a metallic femoral component and a metallic tibial tray. Those TKA designs have sought to increase congruency without increasing the stresses on the implant fixation. In vitro kinematic studies have shown reduced polyethylene wear in mobile bearings because of increased implant conformity and reduced polyethylene contact. In vivo kinematic analysis tends to confirm that mobile-bearing implants allow more natural knee movement. Despite several prospective, randomized studies having been performed, there is no clinical evidence supporting mobile bearing superiority over fixed-bearing designs. Studies focusing on gait parameters, clinical scores, or implant survival failed to confirm in vitro substantial advantage of mobile-bearing implants. More, recent improvement in polyethylene materials might solve wear issues: the last generation of cross-linked polyethylene, associated with a more morphometric design will probably provide superior implant survivorship and more physiological knee biomechanics.

International audience; Relatively poor results have been reported with open reduction and internal fixation of complex fractures around the knee in elderly osteoporotic patients, and primary total knee arthroplasty (TKA) has been proposed as an alternative solution. While limiting the number of procedures, it meets two prerequisites: (1) to save the patient's life, thanks to early weight-bearing, to limit decubitus complications; and (2) to save knee function and patient autonomy, thanks to early knee mobilization. There are 3 main indications: complex articular fractures in elderly patients with symptomatic osteoarthritis prior to fracture; complex articular fractures of the tibial plateau in elderly patients whose bone quality makes internal fixation hazardous; and major destruction of the distal femur in younger patients. Although admitted in emergency, these patients require adequate preoperative management, including a multidisciplinary approach to manage comorbidities, control of anemia and pain, and assessment and management of vascular and cutaneous conditions. Preoperative planning is crucial, to order appropriate implants and materials that may be needed intraoperatively. Surgical technique is based on the basic principles of revision surgery as regards choice of implant, steps of reconstruction, bone defect management and implant fixation. For complex fractures of the distal femur, primary temporary reduction is a useful ``trick'', to determine the level of the joint line and femoral rotation. Complementary internal fixation may be required incase of diaphyseal extension of the fracture and to prevent inter-prosthetic fractures. In the literature, the results of primary TKA for fracture are encouraging and better than for secondary TKA after failure of non-operative treatment or internal fixation, with lower rates of revision and complications, earlier full weight-bearing and better functional results. Loss of autonomy is, however, frequent, and 1-year mortality is high, especially following complex femoral fractures in the elderly. (c) 2017 Elsevier Masson SAS. All rights reserved.

International audience; Increasing use of patient-specific surgical procedures in orthopaedics means that patient-specific anatomical coordinate systems (ACSs) need to be determined. For knee bones, automatic algorithms constructing ACSs exist and are assumed to be more reliable than manual methods, although both approaches are based on non-unique numerical reconstructions of true bone geometries. Furthermore, determining the best algorithms is difficult, as algorithms are evaluated on different datasets. Thus, in this study, we developed 3 algorithms, each with 3 variants, and compared them with 5 from the literature on a dataset comprising 24 lower-limb CT-scans. To evaluate algorithms’ sensitivity to the operator-dependent reconstruction procedure, the tibia, patella and femur of each CT-scan were each reconstructed once by three different operators.Our algorithms use principal inertia axis (PIA), cross-sectional area, surface normal orientations and curvature data to identify the bone region underneath articular surfaces (ASs). Then geometric primitives are fitted to ASs, and the ACSs are constructed from the geometric primitive points and/or axes. For each bone type, the algorithm displaying the least inter-operator variability is identified. The best femur algorithm fits a cylinder to posterior condyle ASs and a sphere to the femoral head, average axis deviations: 0.12°, position differences: 0.20 mm. The best patella algorithm identifies the AS PIAs, average axis deviations: 0.91°, position differences: 0.19 mm. The best tibia algorithm finds the ankle AS center and the 1st PIA of a layer around a plane fitted to condyle ASs, average axis deviations: 0.38°, position differences: 0.27 mm.

International audience; Introduction Due to complex anatomical considerations, results of cementless-stem total hip arthroplasty (THA) in hip fusion remain controversial compared with conventional THA. We therefore aimed to analyse 3D anatomy of the fused hip based on pre-operative computed tomography (CT) scans, functional outcomes based on the Harris Hip Score (HHS) and the Hip Disability and Osteoarthritis Outcome Score (HOOS), modifications of hip anatomy based on post-operative standardised radiography, and determine complication rate and long-term survival based on Kaplan-Meier analysis.Methods We retrospectively studied 23 hips that underwent conversion of a fused hip to THA using a 3D CT scan-based custom titanium (Ti alloy hypoxyapetite (HA)-coated stem. The mean follow-up was 15 (9-22) years. Femur anteversion ranged from -29 degrees to 80 degrees.Results HHS improved from 59 to 89 points and average range of motion (ROM) was 88 degrees for flexion. Back pain decreased in 62%, and knee pain decreased in 42%. The mean post-operative leg-length discrepancy was 7.8 mm. No intra-operative complications occurred. One aseptic stem loosening for mechanical failure was observed. The Kaplan-Meier survivorship considering revision for any reasons as the end point was 95.6% [95% confidence interval (CI) 92.4-98.8] at 15 years.Conclusion Custom cementless stems may be an interesting solution to address the particular anatomical teatimes of hip fusion at the time of THA, with an excellent survival rate at 15 years.

International audience; Background: The aim of this in vitro study was to assess the accuracy of three-dimensional patient-specific cutting guides for open wedge high tibial osteotomy (OWHTO) to provide the planned correction in both frontal and sagittal planes.Methods: Ten cadaveric tibias underwent OWHTO performed using a patient-specific cutting guide based on 3D preoperative planning. An initial CT scan of the tibias was performed, and after segmentation, 3D geometrical models of the pre-OWHTO tibias were obtained. Reference planes were defined, and OWHTO virtually planned to then design patient-specific cutting guides. OWHTO were performed using the patient-specific cutting guides. The patient-specific cutting guide controls the cut and the correction of the OWHTO in both planes. 3D models of post-OWHTO tibias were created after a postoperative CT scan. Geometrical post-OWHTO 3D models were superimposed on pre-OWHTO 3D models. Mechanical medial proximal tibial angle (mMPTA) in the frontal plane and posterior tibial slope (PTS) in the sagittal plane were compared between planned-OWHTO and post-OWHTO 3D reconstructions relative to the pre-OWHTO reference planes and axis. Pearson's and Lin's correlation tests were performed to assess precision and accuracy of patient-specific cutting guides.Results: The mean difference between post-OWHTO and planned-OWHTO was 0.2° (max 0.5°, SD 0.3°) in the frontal plane and − 0.1° (max 0.8°, SD 0.5°) in the sagittal plane. Statistically significant correlations were found between the planned-OWHTO and post-OWHTO configurations for the mMPTA (p

International audience; Background: Tibial implant's positioning in total knee arthroplasty (TKA) requires a compromise between implant's rotation and bone coverage. We hypothesized that morphometric tibial trays (MTTs) would improve implant positioning and clinical outcomes as compared with symmetrical tibial trays.Methods: Thirty-three patients were included prospectively accordingto the following criteria: age from 18 to 85 years, body mass index < 35 kg/m(2), and posterostabilized cemented TKA performed for primary arthritis. Patients were matched for age, gender, body mass index, and preoperative international knee society (IKS) scoring system and Knee Injury and Osteoarthritis Outcome Score (KOOS) pain score, in a 1:1 fashion with patients from a prospectively collected database receiving a symmetrical tibial tray TKA. Tibial implant's rotation, bone coverage, and the percentage of patients with a posterior overhang (PO) >3 mm were assessed using computerized tomography. The IKS and the KOOS were compared at 3-year follow-up.Results: Bone coverage (90% vs 88%, P = .07) and rotation (mean difference 0.7 +/- 3 degrees; P = .69) were not different between the 2 groups. The percentage of patient with a PO was lower in the morphologic group (2/33 vs 14/33, P = .01, odds ratio = 10.3 [2.12-50.24]). Functional scores were superior in the morphometric group: IKS (mean difference 20 +/- 21 points; P = .0005), mainly due to a difference in the IKS pain subscore (mean difference 11 +/- 15 points; P = .0002). According to the multivariate analysis, an MTT had a positive, independent effect on IKS pain (P = .006) and KOOS pain subscores (P = .03) at the last follow-up.Conclusion: The use of an MTT in TKA did not modify the tibial implant position in the axial plane; however, it decreased implant's posterior overhang and improved functional scores. The clinical improvement was mainly found on pain scores.

International audience; Background: Previously published studies reported benefits of computer-assisted surgery (CAS) in terms of radiographic implant position in TKA, but whether these improvements result in clinically important survival differences or functional differences that a patient might perceive at a minimum 10-year followup remains largely unknown.Questions/purposes: We performed a prospective randomized trial and asked whether CAS (1) improved survival free from aseptic loosening; and (2) demonstrated any clear difference in patient-reported outcomes at latest followup using validated outcome measures at minimum 10-year followup.Methods: Between January 2004 and December 2005, 80 patients scheduled for TKA were randomly assigned either to the CAS group or to the conventional technique group by the Hospital Informatics Department. The patient inclusion criteria were age 20 to 80 years old, weight < 100 kg, and consent to receive a primary knee arthroplasty performed through a medial parapatellar approach by the senior author. The exclusion criteria were a history of prior knee surgery, TKA performed for a posttraumatic indication, or revision knee surgery. The first 80 patients meeting these criteria were included in the study. There were 21 women and 19 men and in each group; mean age was 66 years (range, 58-77 years), and mean body mass index was 27 ± 4 kg/m2. An initial published study using this patient group investigated only differences regarding implant positioning in the coronal and sagittal planes. This is a secondary analysis of patients from the earlier study protocol at a minimum of 10-year followup with different endpoints. Kaplan-Meier survivorship was compared between groups, and functional patient-reported outcome measures (PROMs) were evaluated using the SF-12, Knee Injury and Osteoarthritis Outcome Score (KOOS), Forgotten Joint Score, and the new Knee Society Score. Those PROMs were not available at the time of the original randomized controlled trial and we therefore do not have baseline preoperative values demonstrating that our two groups were comparable. However, our groups were created using strict randomization and were similar in terms of demographic parameters and knee deformities. Our secondary analysis was not powered for survival analysis but had 80% power to detect a difference > 6 points on the SF-12 components and > 6 points out of 100 on the KOOS subscores (published minimal clinically important difference: 8 points) at the p < 0.05 level.Results: With the numbers available, there was no difference between the CAS group and the conventional TKA group in terms of survivorship free from aseptic loosening 10 years after TKA (97%, 95% confidence interval [CI], 95%-99% versus 97%, 95% CI, 95%-99%; p = 0.98). Investigation of the latest followup PROM scores showed no difference between SF-12 scores (respectively, for CAS and control patients, physical SF-12: 72 ± 12 versus 73 ± 13 mean difference 0, 95% CI -3 to 3, p = 0.9; mental SF-12: 75 ± 8 versus 73 ± 10, mean difference 2, 95% CI 0−4, p = 0.3) as well as for all KOOS subscores (all p > 0.1). Forgotten Joint Scores were similar in both groups with 83 ± 4 for CAS and 82 ± 5 for control patients (mean difference 1, 95% CI 0−2, p = 0.2). Finally, the new Knee Society Scores were not statistically different between groups with a mean objective score of 82 ± 13 for CAS patients versus 79 ± 12 for control patients (mean difference 2, 95% CI 0−5, p = 0.5) and a mean subjective score of 83 ± 11 versus 85 ± 12, respectively (mean difference 2, 95% CI 0−5, p = 0.5).Conclusions: Our observations suggest that CAS used for TKA alignment with restoration of a neutral mechanical axis as the goal did not confer any substantial advantage in survivorship, function, or quality of life at 10 years after TKA. Larger studies with longitudinal collection of PROMs for functional assessment and greater numbers to assess survivorship are needed to confirm these findings.Level of Evidence:Level III, therapeutic study.

International audience; Increasing use of patient-specific surgical procedures in orthopaedics means that patient-specific anatomical coordinate systems (ACSs) need to be determined. For knee bones, automatic algorithms constructing ACSs exist and are assumed to be more reliable than manual methods, although both approaches are based on non-unique numerical reconstructions of true bone geometries. Furthermore, determining the best algorithms is difficult, as algorithms are evaluated on different datasets. Thus, in this study, we developed 3 algorithms, each with 3 variants, and compared them with 5 from the literature on a dataset comprising 24 lower-limb CT-scans. To evaluate algorithms’ sensitivity to the operator-dependent reconstruction procedure, the tibia, patella and femur of each CT-scan were each reconstructed once by three different operators.Our algorithms use principal inertia axis (PIA), cross-sectional area, surface normal orientations and curvature data to identify the bone region underneath articular surfaces (ASs). Then geometric primitives are fitted to ASs, and the ACSs are constructed from the geometric primitive points and/or axes. For each bone type, the algorithm displaying the least inter-operator variability is identified. The best femur algorithm fits a cylinder to posterior condyle ASs and a sphere to the femoral head, average axis deviations: 0.12°, position differences: 0.20 mm. The best patella algorithm identifies the AS PIAs, average axis deviations: 0.91°, position differences: 0.19 mm. The best tibia algorithm finds the ankle AS center and the 1st PIA of a layer around a plane fitted to condyle ASs, average axis deviations: 0.38°, position differences: 0.27 mm.

International audience; Background: Options for total hip arthroplasty (THA) in high dislocated hips include subtrochanteric osteotomy (STO), high hip center positioning, and 2-stage surgery with progressive lowering using an external fixator before THA. We described the long-term results of 1-stage THA performed without STO, using a cementless customized stem associated if necessary with sequential tenotomies and/or greater trochanteric osteotomy.Methods: Ninety-eight consecutive THA without STO were performed using this technique. Of those 98 hips, 26 hips with high dislocation (12 class III and 14 class IV according to the Crowe classification) were evaluated at an average follow-up of 16 (10-22) years.Results: At the time of last follow-up, the mean Harris Hip Score was 86 points (37-100). The mean leg-length discrepancy was 7 +/- 5 mm (0-17). Two transient (7.7%) nerve palsies (1 sciatic and 1 femoral) were notified. A revision was required for 6 hips (23.1%). Kaplan-Meier survivorship analysis at 15 years regarding aseptic loosening of the femoral component was 87.5% (95% confidence interval, 76.5-99.1). During the same period, acetabular implant survivorship free from revision for aseptic loosening was 96.1% (95% confidence interval, 92.7-99.9).Conclusion: The combination of intramedullary fit and extramedullary adaptation for offset and anteversion provided by the custom stem can avoid additional procedures associated to THA in high developmental dysplasia of the hip. The clinical function and long-term survival reported in this series is encouraging for THA performed in case of high hip dislocation.

Place: Germany; PURPOSE: Management of post-traumatic patellar instability in children with osseous abnormalities is challenging because of the presence of an open physis. The aim of our study was to compare the rate of recurrence after isolated reconstruction of the medial patellofemoral ligament (MPFL) in children with or without osseous abnormalities. METHODS: The medical records of 25 children (27 knees) with recurrent patellar dislocation were reviewed. Each child underwent an isolated reconstruction of the MPFL using a hamstring graft. At the last follow-up, a clinical and radiographic evaluation was performed, including assessment of functional outcomes based on the Kujala score. Patients were compared in terms of the occurrence of a pre-existing osseous abnormality. RESULTS: The mean age at the time of the surgery was 13.8 years. Eleven patients had trochlear dysplasia (40%), three had a patella alta (11%) and seven had an increased TT-TG (26%). The recurrence rate was 3.7% (one patient), after a mean follow-up of 41.1 months. Recurrence was not more frequent in patients with preoperative anatomical predisposing factors. The mean Kujala score was 95. The mean time to return to practicing sports was 7.1 months. CONCLUSIONS: Isolated MPFL reconstruction is an effective option for the management of post-traumatic patellofemoral instability in skeletally immature patients. The results of this technique seem to be independent on either proximal or distal misalignments such as trochlear dysplasia, patella alta, or increased TT-TG.

Objectives. Muscle shortening and spastic cocontraction in ankle plantar flexors may alter gait since early childhood in cerebral palsy (CP). We evaluated gastrosoleus complex (GSC) length, and gastrocnemius medialis (GM) and peroneus longus (PL) activity during swing phase, in very young hemiparetic children with equinovalgus. Methods. This was an observational, retrospective, and monocentric outpatient study in a pediatric hospital. Ten very young hemiparetic children (age 3 ± 1 yrs) were enrolled. These CP children were assessed for muscle extensibility (Tardieu scale XV1) in GSC (angle of arrest during slow-speed passive ankle dorsiflexion with the knee extended) and monitored for GM and PL electromyography (EMG) during the swing phase of gait. The swing phase was divided into three periods (T1, T2, and T3), in which we measured a cocontraction index (CCI), ratio of the Root Mean Square EMG (RMS-EMG) from each muscle during that period to the peak 500 ms RMS-EMG obtained from voluntary plantar flexion during standing on tiptoes (from several 5-second series, the highest RMS value was computed over 500 ms around the peak). Results. On the paretic side: (i) the mean XV1-GSC was 100° (8°) (median (SD)) versus 106° (3°) on the nonparetic side (p=0.032, Mann–Whitney); (ii) XV1-GSC diminished with age between ages of 2 and 5 (Spearman, ρ = 0.019); (iii) CCIGM and CCIPL during swing phase were higher than on the nonparetic side (CCIGM, 0.32 (0.20) versus 0.15 (0.09), p<0.01; CCIPL, 0.52 (0.30) versus 0.24 (0.17), p<0.01), with an early difference significant for PL from T1 (p=0.03). Conclusions. In very young hemiparetic children, the paretic GSC may rapidly shorten in the first years of life. GM and PL cocontraction during swing phase are excessive, which contributes to dynamic equinovalgus. Muscle extensibility (XV1) may have to be monitored and preserved in the first years of life in children with CP. Additional measurements of cocontraction may further help target treatments with botulinum toxin, especially in peroneus longus.

International audience; The function of the hip labrum during hip motion remains poorly known. Our hypothesis was that acetabular labrum will deform and change its shape during adduction to abduction movement consecutively to variation of strains passing from the acetabulum to the femoral head. An ex vivo anatomical study was conducted to analyse the morphological parameters variation of the mid-portion of the labrum (length, thickness, shape, deformation) as well as femoro-labral strains during hip adduction to abduction movement. Ten fresh-frozen, unpaired human cadaver hemi-pelvises were obtained. To best approximate the clinical reality, fresh-frozen cadaver tissues were utilized. The hemi-pelvises were split sagittally in two equal parts through a plane crossing the femoral neck and femoral head centres. The hemi-pelvises were rigidly mounted on a test platform using a custom-made fixture, and a seven hundred Newton load was applied through the iliac wing, with a unidirectional movement (adduction/abduction) of the acetabulum above the fixed femur. Variations of strain passing from the labrum to the femoral head or neck were analysed using captors fixed on the acetabular edge. From 20A degrees to 40A degrees of abduction labral length decreased from a median of 5.8 (5.5-6.4 mm) to 4.6 (4-5.4 mm), labral edge angle increased from a median of 33.1 (31.1A degrees-40A degrees) to 52.3 (41.4A degrees-58.8A degrees), labral sectional area decreased from a median of 22.1 (17-27.1 mm(2)) to 14.2 (12-16.8 mm(2)) all p = 0.001. Femoro-labral strains were maximal at 40A degrees of abduction [median 0.1 N mm(-2) (0.1-3.1 N mm(-2))] and minimal at 30A degrees adduction (median 0 N mm(-2) (0-0.1 N mm(-2)) and p = 0.001). The morphological variations of the mid-portion of the labrum during hip motion reflect strains passing from the labrum to the femoral head. Those elements may provide clues to understand the mechanical role of the labrum during abduction. The acetabular labrum bears a direct mechanical role during hip motion, thus resecting the hip's labrum during surgery might be detrimental for hip joint's biomechanics as it might modify strains distribution between the acetabulum and femur.

International audience; no abstract

International audience; Additive manufacturing methods provide an increasingly popular industrial means of producing complex mechanical parts when classical methods are not suitable. The main advantage of these methods is the great freedom they give designers. At the same time, theoretical and numerical topology optimization tools can be used to simulate structures with complex shapes which exactly meet the mechanical constraints while requiring as little material as possible. Combining topology optimization and additive production procedures therefore seems to be a promising approach for obtaining optimized mechanical parts. Nonetheless structures obtained via topology optimization are composed of parts of composite densities which can not produced via additive manufacturing. Only numerical structures made of full or empty spaces only can be produced by additive methods. This can be obtained at the end of computational optimization through a penalization step which gives the composite densities from 0 to 1 the values 0 or 1. This means that the final part is different from the best solution predicted by topology optimization calculations. It therefore seemed to be worth checking the validity of an engineering approach in which additive methods are used to manufacture structures based on the use of industrial topology optimization codes. Here the authors propose to study, in the case of a simple mechanical problem, that of a metal cube subjected to a given pressure, three procedures, which differed in terms of the code and type of topology optimization calculations performed and the level of penalization applied. The three structures thus obtained were then produced using additive methods. Since all three structures proved to be mechanically resistant, the three procedures used can be said to be valid. However, one of them yielded better compromise between the mechanical strength and the amount of material saved. (C) 2017 The Society of Manufacturing Engineers. Published by Elsevier Ltd. All rights reserved.

International audience; IntroductionTreatment of medial tibiofemoral osteoarthritis with a high-tibial osteotomy (HTO) is most effective when the optimal angular correction is achieved. However, conventional instrumentation is limited when multiplanar correction is needed.HypothesisUse of patient-specific cutting guides (PSCGs) for HTO provides an accurate correction (difference < 2°) relative to the preoperative planning.Materials and methodsBetween February 2014 and February 2015, 10 patients (mean age: 46 years [range: 31–59]; grade 1 or 2 osteoarthritis in Ahlbäck's classification) were included prospectively in this reliability and safety study. All patients were operated using the same medial opening-wedge osteotomy technique. Preoperative planning was based on long-leg radiographs and CT scans with 3D reconstruction. The PSGCs were used to align the osteotomy cut and position the screw holes for the plate. The desired correction was achieved in the three planes when the holes on the plate were aligned with the holes drilled based on the PSCG. Preoperatively, the mean HKA angle was 171.9° (range: 166–179°), the mean proximal tibial angle was 87° (86–88°) and the mean tibial slope was 7.8° (1–22°). The postoperative correction was compared to the planned correction using 3D CT scan transformations. Intraoperative and postoperative complications were assessed at a minimum follow-up of 1 year.ResultsThe procedure was successfully carried out in all patients with the PSCGs. On postoperative long-leg radiographs, the mean HKA was 182.3° (180–185°); on the CT scan, the mean tibial mechanical angle was 94° (90–98°) and the mean tibial slope was 7.1° (4–11°). In 19 out of 20 postoperative HKA and slope measurements, the difference between the planned and achieved correction was < 2° based on the 3D analysis of the three planes in space; in the other case, the slope was 13° instead of the planned 10°. The intra-class correlation coefficients between the postoperative and planned parameters were 0.98 [0.92–0.99] for the HKA and 0.96 [0.79–0.99] for the tibial slope. There were no surgical site infections; one patient had a postoperative hematoma that resolved spontaneously.DiscussionThe results of this study showed that use of PSCGs in HTO procedures helps to achieve optimal correction in a safe and reliable manner.Level of evidenceIV – Prospective cohort study.Keywords: Medial tibiofemoral osteoarthritis, High tibial osteotomy, Opening-wedge osteotomy, Patient-specific surgical guides, 3D printing

International audience; Objective: Intraarticular or periarticular injection of ropivacaine (RI) is an element of current knee surgery practices. The goal of this study was to determine the effects of RI on the mechanical properties of hamstring tendons. We hypothesized that RI would have a detrimental effect on the mechanical properties of periarticular soft tissuesMethods: A tensile test to failure was performed on 120 hamstring tendon segments harvested during ACL reconstruction surgery in 120 patients. Two sets of tensile tests were done. The first evaluated the effect of RI itself on the mechanical properties of tendons: 30 samples were soaked for 1 hour in a 2% RI solution and compared to 30 samples soaked in a saline solution (control group). The second evaluated the effect of RI concentration on the mechanical properties of hamstring tendons: 30 samples were soaked for 1 hour in a 2% RI solution and 30 samples were soaked in a 7.5% RI solution.Results: In the first test, 29 samples from each group were analyzed as two samples (one in each group) failed at the grip interface. The specimens exposed to 2% RI had lower ultimate tensile strength (= 4.4 MPa, P = 0.001), strain energy (= 13 MPa, P = 0.001) and Young's modulus (= 1.6 MPa, P = 0.02) than the specimens in the control group. There was no significant difference in the strain at failure between groups (= 5%, P = 0.3). In the second test, one specimen from the 7.5% RI group failed during the preloading and was excluded. There was no significant difference in terms of the load at failure and ultimate tensile stress (= 0.45 MPa, P = 0.6) and strain energy (= 0.49 MPa, P = 0.49) between the two groups. There were significant differences in terms of elongation at failure (= 28%, P = 0.0003) and Young's modulus (= 2.6 MPa, P = 0.005), with the specimens exposed to 7.5% RI undergoing greater deformation and having a lower Young's modulus.Discussion: While local RI injections are widely performed in clinical practice, the results of this in vitro study point to short-term alterations of the mechanical properties of hamstring tendons. If these results hold in vivo, this could lead to weakness of the soft tissues exposed to this product, particularly the tendons and ligaments around the injection area.Level of evidence: Experimental study. Level 1

International audience; The influence of neuromuscular electrical stimulation (NMES) parameters on brain activation has been scarcely investigated. We aimed at comparing two frequently used NMES protocols-designed to vary in the extent of sensory input. Whole-brain functional magnetic resonance imaging was performed in sixteen healthy subjects during wide-pulse high-frequency (WPHF, 100 Hz–1 ms) and conventional (CONV, 25 Hz–0.05 ms) NMES applied over the triceps surae. Each protocol included 20 isometric contractions performed at 10% of maximal force. Voluntary plantar flexions (VOL) were performed as control trial. Mean force was not different among the three protocols, however, total current charge was higher for WPHF than for CONV. All protocols elicited significant activations of the sensorimotor network, cerebellum and thalamus. WPHF resulted in lower deactivation in the secondary somatosensory cortex and precuneus. Bilateral thalami and caudate nuclei were hyperactivated for CONV. The modulation of the NMES parameters resulted in differently activated/deactivated regions related to total current charge of the stimulation but not to mean force. By targeting different cerebral brain regions, the two NMES protocols might allow for individually-designed rehabilitation training in patients who can no longer execute voluntary movements. Neuromuscular electrical stimulation (NMES) consists of a series of intermittent electrical stimuli applied over the muscle or the nerve trunk in order to elicit isometric muscle contractions. NMES has emerged as an efficient tool to induce activity-dependent plasticity in neural circuits in both healthy subjects 1, 2 and hypoactive patients with stroke 3–5. For instance, changes in corticospinal excitability resulting from a single session of NMES have been reported for a variety of upper 6, 7 and lower 8 limb muscles. Accordingly, functional magnetic resonance imaging (fMRI) investigations revealed a widespread brain activation pattern in response to NMES of different muscle groups, including the contralateral primary motor (M1) and sensory (S1) cortices, secondary somatosen-sory area (S2), supplementary motor area (SMA) and prefrontal cortex 9–13. Despite the promise of NMES as a tool for driving neuroplasticity and improving motor function 3–5 , the influence of stimulation parameters on the magnitude of sensory inputs to the brain has been scarcely investigated. A few studies have only reported a dose-response relationship between either stimulation intensity 10, 14 or pulse frequency 15 and brain activation patterns. From a neuromuscular point of view, NMES-induced isometric contractions may arise from the direct activation of motor axons (i.e., efferent pathway) and/or from the recruitment of motoneurons in the spinal cord through the depolarization of sensory axons (i.e., afferent pathway). It has been reported that NMES parameters, such as stimulation intensity, pulse frequency and pulse duration, affect the relative contribution of efferent and afferent pathways to force production 16. Conventional (defined hereafter as CONV) NMES protocols typically consist of short pulses (

International audience; Introduction: Severe pelvic trauma remains associated with elevated mortality, largely due to hemorrhagic shock. Objective: The main study objective was to test for correlation between fracture type and mortality. The secondary objective was to assess the efficacy in terms of mortality of multidisciplinary management following a decision-tree in multiple trauma victims admitted to a level 1 trauma center. Material and methods: Between July 2011 and July 2013, 534 severe trauma patients were included in a single-center continuous prospective observational study. All patients with hemorrhagic shock received early treatment by pelvic binder. Patients with active bleeding on full-body CT or persisting hemorrhagic shock underwent arteriography with or without embolization. Pelvic trauma was graded on the Tile classification. The principle end-point was mortality. Results: Median age was 40 years (range, 26-48 years), with a 79% male/female sex ratio. Thirty-two of the 67 patients with pelvic trauma (48%) were in hemorrhagic shock at admission. Median injury severity score (ISS) was 36 (range, 24-43). On the Tile classification, 22 patients (33%) were grade A, 33 (49%) grade B and 12 (18%) grade C. Overall mortality was 19%, and 42% in case of hemorrhagic shock. Mortality was significantly higher with Tile C than A or B (58% vs. 9.1% and 12.1%, respectively; P = 0.001). Conclusion: Vertical shear fracture (Tile C) was associated with greater mortality from hemorrhagic shock. (C) 2016 Elsevier Masson SAS. All rights reserved.

International audience; The aim of this study was to analyze first intraoperative alignment and reason to abandon the use of patient-specific instrumentation using intraoperative CAS measurement, secondly assess by postoperative CT analysis if CI, based on preoperative 3D-MRI data, improved postoperative component positioning (including femoral rotation) and lower limb alignment as compared with results obtained with CAS. In this randomized controlled trial, 80 consecutive patients scheduled to undergo TKA were enrolled. Eligible knees were randomized to the group of PSI-TKAs (n = 40) or to the group of CAS-TKAs (n = 40). In the CAS group, CAS determined and controlled cutting block positioning in each plane. In the PSI group, CAS allowed to measure adequacy of intraoperative alignment including femoral component rotation. At 3 months after surgery, implants position were measured and analyzed with full-weight bearing plain radiographs and CT scan. Intraoperatively, there was a significant difference concerning Sagittal Femoral mechanical, Frontal tibial mechanical angle and tibial slope between the two groups (respectively p = 0.01, p = 0.02, p = 0.046). Custom instrumentation was abandoned intraoperatively in seven knees (17.5 %). Abnormal tibial cuts were responsible of the abandon in three out of seven cases, femoral cut in 1/7 and dual abnormalities in 3/7. Postoperatively, tibial slope outliers percentage was higher in the patient specific instrumentation group with six patients (18.18 %) versus one patient (2.5 %) in the CAS group (p = 0.041). Patient specific instrumentation was associated with an important number of hazardous cut and a higher rate of outliers in our series and thus should be used with caution as related to. This study is the first to our acknowledgement to compare intra-operative ancillary and implant positioning of PSI-TKA and CAS-TKA. High rate of malposition are sustained by our findings, as such PSI-TKA should be used with caution, by surgeons capable to switch to conventional instrumentation intra-operatively. Randomized control trial, Level I.

International audience; Background: Successful management of large bone defects is of crucial importance when performing revision total knee arthroplasty (TKA). Trabecular tantalum cones may improve prosthesis fixation via their potential for reconstructing a stable metaphyseal support. The objective of this study was to evaluate the clinical and radiological outcomes and the complications of tantalum cones in revision TKA. Hypothesis: Trabecular tantalum cones provide stable and durable metaphyseal reconstruction when used during revision TKA. Material and methods: Trabecular Metal (TM) cones (Zimmer, Warsaw, IN, USA) were used for 52 revision TKAs in 51 patients (mean age, 68 +/- 9 years) managed in two centres between 2008 and 2013. A rotating hinge prosthesis was chosen for 38 (73%) knees and a condylar constrained knee prosthesis for 14 (27%) knees, with 37 tibial and 34 femoral cones. The two most common reasons for revision surgery were aseptic loosening (n= 22, 42%) and infection (n=19, 37%). The bone loss was severe in most cases. At each centre, after a mean follow-up of 34 months (range, 24-52 months), two independent observers assessed the Knee Society Score (KSS), range of motion, mechanical axis, and osteo-integration for each patient. Results: Mean KSS increased from 46 preoperatively to 77 (P=0.001) at last follow-up and the mean KSS function from 39 to 57 (P=0.007). Mean range of motion improved from 93 degrees (45 degrees-120 degrees) to 110 (65 degrees-130 degrees) (P= 0.001). Mean postoperative mechanical axis was 180 degrees (172 degrees-190 degrees). Radiographic evaluation showed evidence of osteo-integration for all cones. Four revisions were performed for recurrence of infection but none for mechanical failure. Discussion: The findings of our study confirm the biomechanical and biological reliability of Trabecular Metal (TM) cones used to fill metaphyseal bone defects during revision TKA. Level of evidence: IV, retrospective therapeutic study. (C) 2016 Elsevier Masson SAS. All rights reserved.

International audience; Restoration of normal hip biomechanics is a key goal of total hip arthroplasty (THA) and favorably affects functional recovery. Furthermore, a major concern for both the surgeon and the patient is preservation or restoration of limb length equality, which must be achieved without compromising the stability of the prosthesis. Here, definitions are given for anatomic and functional limb length discrepancies and for femoral and hip offset, determined taking anteversion into account. Data on the influence of operated-limb length and offset on patient satisfaction, hip function, and prosthesis survival after THA are reviewed. Errors may adversely impact function, quality of life, and prosthetic survival and may also generate conflicts between the surgeon and patient. Surgeons rely on two- or three-dimensional preoperative templating and on intraoperative landmarks to manage offset and length. Accuracy can be improved by using computer-assisted planning or surgery and the more recently introduced EOS imaging system. The prosthetic's armamentarium now includes varus-aligned and lateralized implants, as well as implants with modular or custom-made necks, which allow restoration of the normal hip geometry, most notably in patients with coxa vara or coxa valga. Femoral anteversion must also receive careful attention. The most common errors are limb lengthening and a decrease in hip offset. When symptoms are caused by an error in length and/or offset, revision arthroplasty may deserve consideration. (C) 2015 Elsevier Masson SAS. All rights reserved.

International audience; Most acetabular cups implanted today are press-fit impacted cementless. Anchorage begins with the primary stability given by insertion of a slightly oversized cup. This primary stability is key to obtaining bone ingrowth and secondary stability. We tested the hypothesis that primary stability of the cup is related to surface roughness of the implant, using both an experimental and a numerical models to analyze how three levels of surface roughness (micro, macro and combined) affect the primary stability of the cup. We also investigated the effect of differences in diameter between the cup and its substrate, and of insertion force, on the cups' primary stability. The results of our study show that primary stability depends on the surface roughness of the cup. The presence of macro-roughness on the peripheral ring is found to decrease primary stability; there was excessive abrasion of the substrate, damaging it and leading to poor primary stability. Numerical modeling indicates that oversizing the cup compared to its substrate has an impact on primary stability, as has insertion force. (C) 2014 IPEM. Published by Elsevier Ltd. All rights reserved.

International audience; Objectives: To correlate magnetic resonance imaging (MRI) aspects of the femoral head with histological findings in advanced hip osteoarthritis (OA), with special emphasis on bone marrow edema (BME).Methods: MRI was performed in patients with advanced hip OA scheduled for hip arthroplasty. Coronal T1-, fat-suppressed T2-, T1 with gadolinium intravenous injection sequences were obtained on a 1.5T MR-scanner within 1 month before surgery. Coronal MR images corresponding to the ligamentum teres plane were analyzed by two independent readers blinded to histological data. Normal bone marrow, subchondral cyst, subchondral fracture, edema-like, necrosis-like, and necrosis MR patterns were reported on a synthesis scheme. After surgery, the femoral heads specimens were cut through the ligamentum teres plane and histologically analyzed for correlations.Results: Twenty-three femoral heads were analyzed (female 56.5%, mean age 64.5 years). Edema-like MR pattern was correlated with histological (H) edema (Kappa (K): 0.77). Necrosis-like MR pattern was correlated with H fibrosis (K: 0.49) and with H necrosis (K: 0.24). Cyst MR pattern was correlated with H bone cysts (K: 0.58). Necrosis MR pattern corresponded to a mixture of histological lesions. Sensitivity and specificity of MRI varied from 26% to 80% and from 86% to 95% respectively.Conclusion: In advanced hip OA, the so-called ``BME'' MR lesion corresponds to a combination of edema, fibrosis, and necrosis at histopathology. When the classical ``BME'' is more specifically separated into edema-like and necrosis-like MR patterns, MR Imaging and histological findings show substantial agreement, with edema-like MR pattern mainly corresponding to histological edema.

110th Annual Meeting of the American-Roentgen-Ray-Society, San Diego, CA, MAY 02-07, 2010; International audience; no abstract